What proportion of basal and squamous cell skin cancers are not completely excised?

Linked Article:   Nolan et al. Br J Dermatol 2021; 184 :1033–1044. Basal cell and squamous cell skin cancers (BCCs and SCCs, or ‘keratinocyte’ cancers) are the commonest cancers worldwide. They are usually treated by surgical excision – that is, by cutting them out. This is usually done in hospital but may be done by family doctors. It is important to know if such cancers are completely excised because each year they together account for 20% of all new cancers in the UK and cost the National Health Service over £180 million to treat. Incomplete excisions, where cancer cells are left behind, place an extra burden on patients and health services. A study analysing results from multiple separate studies is a ‘meta‐analysis’. This meta‐analysis from the UK examined 110 studies of skin cancer treatment published since 2000 where the proportion of keratinocyte cancers that were incompletely excised was recorded. Each study included more than 50 adult patients and met criteria set by the authors. Patients having Mohs surgery, for instance, where the edges of excision specimens are examined by a pathologist while the operator waits, were excluded. Combined, these studies contained information on over 50,000 patients with over 100,000 BCCs and over 20,000 SCCs. The overall proportion of BCCs incompletely excised was 11%, and of SCCs 9·4%. These proportions were lowest for dermatologists and highest for family doctors, whereas plastic surgeons and other specialized surgeons, who deal with cancers that need more complicated surgery, were in between. The proportions are higher than those in current guidelines, which the authors suggest should be updated.